“… The object of your mission is to explore the Missouri river, & such principal stream of it, as, by it’s course & communication with the waters of the Pacific Ocean, may offer the most direct & practicable water communication across this continent, for the purposes of commerce.

Beginning at the mouth of the Missouri, you will take observations of latitude & longitude, at all remarkable points on the river, & especially at the mouths of rivers, at rapids, at islands & other places & objects distinguished by such natural marks & characters of a durable kind, as that they may with certainty be recognized hereafter. the courses of the river between these points of observation may be supplied by the compass, the log–line & by time, corrected by the observations themselves. the variations of the compass too, in different places, should be noticed.

… Your observations are to be taken with great pains & accuracy, to be entered distinctly, & intelligibly for others as well as yourself, to comprehend all the elements necessary….”

– Excerpts from the diaries of Thomas Jefferson